Apparatus for sweating or crystallizing paraffin or other wax



Aug. 12 1924. `1,504,923

H. L. ALLAN ET AL APPARATUS FOR SWEATING OR CRYSTALLIZING PARAFFIN OR OTHER WAX Filed OCT.. 6, 1923 3 Sheets-Sheet l Flgl. y 2

Y yf//X COMPAET T ET Aug. 12 1924. 1,504,923

H. L. ALLAN ET AL APPARATUS FOR SWEATING OR CRYSTALLIZING PARAFFIN OR OTHER WAX Filed OGL. 6. 1925 5 Sheets-Sheet 2 Aug. l2 1924.

H. L. ALLAN T AL APPARATUS FOR SWEATING OR CRYSTALLIZING PARAFFIN OR OTHER WAX 3 Sheets-Sheet.

Filed Oct. 6

34, www?? 7 0 an STE/9M ggf; rim 31,2, 33

Patented Aug. 12, 1924.

UNITED STATES PATENT OFFICE.

HUGH Il. ALLAN AND JAMES MOORE, OF BURMAI-I, BRITISH INDIA, ASSIGNORS TO THE BURMAH OIL COMPANY LIMITED, 0F GLASGOW, SCOTLAND, A BRITISH CORPORA- TIO'N.

APPARATUS FOR SWEATING OR CRYSTALLIZING PARAFFI'N OR OTHER WAX.

Application filed October 6, 1923. Serial No. 666,996.

To all whom t may concern:

Be it known that we, HUGH Locm ALLAN and JAMES MOORE, British subjects, and both residents of Burmah, British India, have invented certain new and useful Improvements in Apparatus for Sweating or Crystallizing Paraifin or Other Wax, of which the Afollowing is a specification.

rIhis invention relates to the manufacture of waxes more particularly paraffin wax, vand has for its object to provide an improved stove or apparatus for crystallizing and (or) sweating the parafiin or other wax.

Heretofore it has been usual to depend upon an air circulating system for cooling the scale (wax and oil mixture or waxes of different melting points), particularly when the wax is cooled in trays by air or by the combination of air on the surface and water coils at the bottom of the trays.

In the present invention the wax is kept out of direct-contact with air and the tray is covered to form a wax chamber or compartment, and provision is made for effecting uniform heating or cooling of the wax throughout the compartment for which purpose the top and bottom of the compartment may be in contact with water or other cooling or heating liquid.

By this system, complete temperature control can be obtained and, at the same time, more rapid conduction of heat for the same temperature difference between oil and a water-Cooled surface than can be obtained between oil and an air-cooled surface. The crystallization can be controlled and the formation of undesirable types of crystals avoided.

In like manner, during sweating, the cake of solidified wax crystals, or crystals and oil, is under complete temperature control and thus even sweating is ensured.

In existing apparatus in which surface cooling of the oil or wax is effected by exposure to air, the surface is more rapidly cooled than the mass, thus tending to the formation of foliaceous crystals which occlude oil, instead of producing acicular crystals from which the oil or lower meltingpoint waxes drain freely.

Furthermore, in existing apparatus in which the wax is supported on horizontal gauze, it is found necessary to have water below the gauze in each tray or section, to support the liquefied charge until cooled to the solid phase and the water is drained off before sweating.

According to the present invention, the' stove or apparatus preferably comprises a plurality of superposed spaced substantially horizontal plate cells through which a cooling or heating medium may be circulated as desired. The cells are enclosed in an outer shell or vessel of metal or other suitable material which may be jacketed or covered externally with suitable lagging or insulation. Passing through the cells is a charging pipe which may be connected to a pump or other char `ng apparatus. The spaces `between the ce ls form wax and oil chambers, each having a raised gauze licor. The charging pipe opens into each wax chamber below the gauze and a vent orifice leads from the top of each wax chamber to an air vent or pipe at the top of the outer shell or vessel for the escape of air during charging and for controlled air admission during cooling and sweating.

Preferably a steam pipe passes through the charging pipe to enable the latter to be cleared of solidified wax before sweating. The charging pipe may also have a drain pipe for carrying off sweatings and the fin` ished product.

In the apparatus herein described, the use, of-water in the wax and oil chamber below the gauze is dispensed with, thus eliminating the necessity for periodically cleaning out the sludge left in the usual trays by the water. A clear space below the gauze is obtained in our apparatus by passing steam or hot water, for a short'time through the water cells, after the mass has been cooled, thus melting the wax contained below the gauze and allowing it to run off' through the drain pipe.

The invention is hereafter described with reference to the accompanying drawings which illustrate one construction of our improved wax stove by way of example.

Fig. 1 is a vertical` section through the stove, with parts broken away and showing to Fig. 1. Fig. 4 shows details of one of the heating elements and Fig. 5 is a detail View showing the wax cake (partially sweated) between two heating elements.

In the constructional example illustrated, an outer cylindrical shell 10 surrounds an inner shell 11 so as to form a water jacket 12. The inner shell 11 encloses a plurality of cells 13, through which water or steam can be circulated as may be desired. Each cell is preferably slightly inclined as seen in Fig. 1. An oil supply pipe 14 supplies the oil from a pump or other charging apparatus to a cell-charging and sweats-outlet pipe 15 through a valve 16. The spaces between the cells 13 form wax compart- 'inents 17 each having a wax-supporting gauze 18 resting on iron rods 19 or other supports. The pipe 15 opens not only into the lowermost compartment 17, but also into an inter-cell charging and sweats-outlet pipe 15a which in turn opens into the next cell 17 and also into a similar inter-cell charging and sweats-outlet pipe 15", and so on throughout the series of cells. Each compartment 17 also has an air pipe 2O which is open to the compartment at the highest point thereof, for .the escape of air displaced ,during charging and for vair admission during sweating. Through the series of' pipes 15, 15a, 15", 15, passes a steam pipe 21 and similarly a steam pipe 22 passes through the air pipe 20 for the purpose of clearing the pipes of wax before sweating. The pipe 15 also has a branch 23 to run olf the sweatings andfinished product. The uppermost air pipe 2O has an oil overflow pipe 24, a steam or scavenging fluid inlet pipe 25 and a'n air inlet and outlet pipe 26, the latter controlled by a double-action valve or check-valve 27 actuated by pressure or suction. The lowermost air pipe 20 opens into an oil drain 28. The compartments 17 are each as shown, provided with a plurality of heatin elements 29 (Fig. 4) hung from the ce ls 13 and open at each end at 30 and 31 to the interior of the cell. Water is circulated through the cells by way of inlet pipes 32 and it will be readily seen, on reference to Fig. 2, that the water circulates in a circuitous or sinuous path through the cells 13, its course being interrupted by baliies, partitions or bars 33 which separate the cells into chambers, adjacent chambers being interconnected by the heating elements 29. The water leaves the cells by pipes 34 and may be led into the water jacket 12 by pipes 35, leaving the water jacket by the outlet 36. The water pipes 35 may be fitted with thermometer cups 37 and regulating valves 38. A sludge or drain cock 39 may be fitted to the water 'acket 12.

The mo e of operation of the apparatus is as follows Water or other liquid at a temperature slightly above the melting point of the scale or wax mixture to be treated is circulated through the cells 13. The wax mixture is then pumped or fed by gravity through the charging pipe 14 and pipe 15 into the lower wax chamber 17 in which it rises, the displaced air escaping through the air vent 40 of the air pipe 20 into the upper chamber 17. The lower chamber 17 fills completely, as the air vent 40 is at the highest possible point therein. When the lower chamber 17 is full, the charge continues to rise successively through pipes 15a, 15b etc. and fills the upper chambers 17 in succession in the same manner. 1

The oil is now drained from the air pipes 20 through the pipe 28, air being allowed to enter the chambers 17 by way of' the air inlet pipe 26, thus ensuring that a vacuum is not created in the apparatus. Hot air is preferably admitted through the pi e 26, to prevent chilling of the surface o t e oil or wax in the compartments 17 The circulating water entering the pipes 32 is then gradually reduced in temperature, the rate of cooling being suited to the nature of the charge. When the charge is cooled to the desired temperature, a period of rest may be given to establish the crystals.

The valve on branch 23 is then opened, steam is passed through the steam pipe 21 in order to clear the pipes 15, 15", etc., of solidified scale and sweating is then begun by gradually raising the temperature of the water circulating through the cells 13. Sweating is continued as long as desired and the sweated wax is finally melted out by raising the temperature of the cells 13 by admitting hot water or steam through the pipes 32 or by admitting steam openly or freely to the wax chambers 17 through the steam pipe 25.

In order to promote eliicient drainage of the wax during sweating, the centre of the wax cake between each vertical element 29 is preferably supported by a gauze artition 41 set vertically along the centre o each space between the vertical elements (see Fig. 5) and the heating elements 29 are surrounded by gauze 42 which extends about half way up the sides of the heating elements and inner shell. As will be seen, by referenceto Fig. 5, this arrangement ensures that the wax surface forms a shed from which the sweats readily drain. The wax cake is'also supported thereby against sa gin y t e improved apparatus, gradual cooling can be effected durin formation of the crystals and the formation of undesirable types of crystals thus avoided. All risk of sudden chillin of any part of the charge is eliminated and fully sweated and purified vwax can be produced in a greater quantity in one operation from a given charge of place scale or mixture of waxes and/or wax oil of a given melting point and colour than in any known apparatus. Dust or other for eign mat-ter is excluded and as the wax chambers are substantially horizontal, we avoid the disadvantages common to known apparatus of the concentric vertical tube type, in'which the wax is supported in the annular space between the tubes and in which sagging of the mass during sweating is common, thus occluding oil or other impurity.

rlhe improved apparatus also permits a thicker cake of mixture to be sweated than can be efficiently sweated in the usual tray type of stove or sweating plant.

The improved apparatus is particularly adapted for the manufacture of paraffin waxes from crude paraffin scale or the like, a feature of the apparatus being its ease of control and the minimum amount of labour required to. operate it. The apparatus also does not require to be housed in a speciallyconstructed building, such as a speciallyheated building.

Claims:

1. Apparatus for crystallizing and drysweating wax comprising a closed wax-containing chamber, substantially horizontal; hollow'heating and cooling cells above and below said chamber, a filling pipe entering said chamber from below and an air-vent at the to of Said. chamber for the escape of disair, whereby said chamber may be completely filled with wax mixture to the exclusion ot air.

2. Apparatus for crystallizing and drysweating wax as claimed in claim l having heatin and cooling elements distributed throug out the interior of the wax-containing chamber and a connection from said elements to the hollow cells.

3. Apparatus for crystallizing `or sweating wax comprising a plurality of superposed, spaced substantially horizontally heating or cooling cells, a casing enclosing the spaces between said cells to provide enclosed intermediate wax compartments, air vents for said compartments, wax-charging and sweats-discharging means for said compartments, a raised perforated wax support in each compartment and vertical perforated partitions extending upwardly from said support.

4. Apparatus for crystallizing or sweating wax comprising a plurality of superposed, spaced substantially horizontal heating or cooling cells, a casing enclosin the spaces between said cells to provide enc osed intermediate wax compartments, air vents for said compartments, wax-charging and sweats-discharging means for said compartments, heat-exchange elements extending into the wax compartment from the cells and open to the interior of said cells.

5. Apparatus for crystallizing or sweatmg wax comprising a plurality of superposed, spaced substantially horizontal heatmg or cooling cells, a casing enclosing the spaces between said cells to provide enclosed intermediate wax compartments, air vents for said( compartments, wax-charging and sweats-discharging means for said compartments, heat-exchange elements extending into the wax compartments from the cells and open to the interior of said cells and perforated wax supports surrounding said elements.

6. Apparatus for crystallizing or sweating wax comprising a plurality of superposed, spaced substantially horizontal heating or cooling cells, a casing enclosing the spaces between saidcells to provide enclosed intermediate wax compartments, air vents for said compartments, wax-charging and sweats-discharging means for said compartments, heat-exchange elements extending into the wax compartments from the cells and open to the interior of said cells and perforated partitions between said elements for supporting the center of the wax cake between adjacent elements.

7. Apparatus for crystallizing or sweating wax comprising a plurality of superposed, spaced substantially horizontal heating or cooling cells, a casing enclosing the spaces between said cells to provide enclosed intermediate wax compartments, air vents for said compartments, a series of coaxial superposed charging and dischargingpipes, each opening upwardly into one of the compartments, and an inlet and outlet connection to the lowermost of said pipes.

8. Apparatus for crystallizing or sweating wax comprising a plurality of superposed, spaced substantially horizontal heating or cooling cells, a casing enclosing the spaces between said cells to provide enclosed intermediate wax compartments, a wax-charging and sweats-discharging device for said compartments, a series of air pipes, each opening into the upper part of one compartment and into the adjacent air pipe, an outlet drain for the lowermost pipe, and a valve controlled air inlet or outlet pipe connecting with'the uppermost pipe.

9. Apparatus for crystallizing or sweating wax comprising a plurality of superposed, spaced substantially horizontal heating or cooling cells, a casing enclosing the spaces between said cells to provide enclosed intermediate wax compartments, air` vents for said compartments, wax-charging and sweats-discharging means for said compartments, heat-exchange elements extending into the wax compartments from the cells and open to the interior of said cells and partitions separating said cells into separate chambers interconnected by said elements.

10. Apparatus forcrystallizing or sweatcompartments, an air vent substantially at the highest point of each compartment and a combined charging inlet and discharging outlet substantially at the lowest point of each compartment. 10

In testimony whereof we hereunto aiix HUGH L. ALLAN. JAMES MOORE.

our signatures. 

